soql – How to retrieve reportFolder.meta-xml files with the Access Type and ParentId attributes?

In your package.xml you have to include report folder name and report name as follow:

<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
        <types>
                <members>MyFolder</members>
                <members>MyFolder/Report1</members>
                <members>MyFolder/Report2</members>
                <name>Report</name>
        </types>
</Package>

Please note <members>MyFolder</members>, this is the important part for you.
The same apply for dashboard folders and email folders.
If you want to retrieve just the folder metadata you can also use sfdx cmd:

sfdx force:source:retrieve -m Reportfolder:MyFolder